Thank you all for your input. I finally found a reason to use my hex editor after reading up on PICT header formats and attempting bit operations in code. No luck though, but interesting enough as a hobby project :)

Still rsr conversion is a minor item being the extreme exception and not the rule; I'm going to log the archives that have RSR thumbnails with no matching PNG's and then use my original GUI RSR program to convert them as a manual step then reprocess the extracted archives.

I did send Dizzi an IM so I'll wait to see if I get a response.

My first go at the null header block didn't work, so from a programatic point of view that's the direction I'll keep experimenting with for now. I just need a better understanding of the PICT header at the byte level.

Just as an FYI for all those who also helped with my last thread, this is a tangential project  to the Cloud Rendering thread I posted a while back (I'm still working on it! lol).

 

~ R